JP5300786B2 - Fuel injection valve drive control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for drive and control of a fuel injection valve in an internal combustion engine, surely diagnosing deterioration of a boost capacitor as soon as possible without error and without stopping boosting operation. <P>SOLUTION: The device includes a boost circuit 30 which has a boost coil 10, a switching element 11 supplying a switching current from the voltage VB of a battery power source to the boost coil 10, and the boost capacitor 14 storing the boosted voltage generated by switching operation of the switching element 11. The device, until a predetermined time elapses from the time point when the boosted voltage Vs stored in the boost capacitor 14 reaches a predetermined voltage VH, counts the number of the switching operation of the switching element 11 and diagnoses deterioration of the boost capacitor 14 based on the counted value. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a fuel injection valve drive control device for an internal combustion engine mounted on an automobile or the like that uses gasoline or light oil as fuel, and more particularly, to drive an electromagnetic fuel injection valve using a high voltage boosted from an in-vehicle battery. The present invention relates to a fuel injection valve drive control device that performs control.

  In general, in a fuel injection valve drive control device that performs drive control of an electromagnetic fuel injection valve, as shown in Patent Document 1, for example, the fuel injection valve (solenoid) is quickly opened at the initial stage of energization. For this purpose, a relatively large peak current (indicated by symbol Ia in FIG. 5 showing a typical example of a current waveform supplied to the fuel injection valve) is supplied, and then the valve opening state is maintained. In order to supply the first hold current Ib and the second hold current Ic, the fuel injection valve drive control device 2 normally has a booster coil 10, a switching element, for example, as shown in FIG. 11, a current detection resistor 12, a boost diode 13, a boost capacitor 14, etc., a boost circuit 30, a high side driver 41, backflow prevention diodes 42 and 44, a flywheel Diode 45, high-side driver 43, a drive circuit 40 of the low-side driver 46, the fuel injection valve 70 consisting of the drive current detection resistor 47 or the like, the control unit (ECU) 100 incorporating a microcomputer is provided.

  The control unit 100 is functionally provided with a boost control means 20 and a drive control means 50. As shown in the functional block diagram, the boost control means 20 includes a boost control signal generation means 21, a current detection means 22, Boosted voltage detection means 23 is provided. Here, when the switching element 11 is turned on by a signal from the boost control signal generating means 21, a current flows through the boosting coil 10, and when the switching element 11 is subsequently turned off, the current flowing through the boosting coil 10 cannot be changed suddenly. As a result, a current flows through the boost capacitor 14. By repeating such a switching operation, a high voltage is stored in the boost capacitor 14 (boost voltage Vs).

  In the fuel injection valve drive control device 2 provided with the booster circuit 30, when supplying the initial peak current Ia, the drive control means is used to use the boosted voltage Vs as a current supply source to the fuel injector 70. 50 controls the high-side driver 41 and the low-side driver 46 connected to the boost capacitor 14. In supplying the first hold current Ib and the second hold current Ic, the current supply source to the fuel injection valve 70 is switched from the boosted voltage Vs to the battery power supply voltage VB and connected to the battery power supply voltage VB. The high side driver 43 and the low side driver 46 are controlled. The current supplied to the high-side driver 41, the high-side driver 43, and the low-side driver 46 is converted into a voltage by a current detection resistor 47 disposed on the downstream side of the low-side driver 46, and fed back to the drive control means 50 for current control. Is done.

JP 2009-108686 A JP 2003-127822 A

  However, in the conventional fuel injection valve drive control device 2 as described above, if the booster circuit 30 fails, the required boosted voltage Vs cannot be obtained, and the peak current Ia cannot be supplied to the fuel injector.

  Therefore, as a countermeasure against the booster circuit failure, for example, in Patent Document 1, the failure of the booster circuit is detected by monitoring the peak current with the current detection resistor arranged on the downstream side of the low-side driver or by monitoring the boosted voltage itself. Hold current required to excite the solenoid of the fuel injection valve using the battery power supply voltage without using the boosted voltage to open the fuel injection valve, and hold current required to maintain the open state of the fuel injection valve Is generated and supplied.

  However, in the boost circuit failure detection method as described above, it may be erroneously determined that it has failed even though it has not actually failed, and the fuel injection valve is driven without using the boost circuit. As a result, the original fuel injection valve drive current cannot be obtained, and therefore the fuel injection valve cannot be opened quickly, resulting in a decrease in valve opening response, deterioration in control accuracy, fuel consumption, and the like.

  Therefore, there is a demand for a measure that can detect a failure of the booster circuit at an early stage without fail and can quickly return to the original operation.

  Incidentally, the failure of the booster circuit as described above is often caused by the deterioration of the booster capacitor 14. In other words, normally, electrolytic capacitors that are relatively inexpensive and have a large capacity are widely used as boost capacitors in order to keep the boost voltage stable. However, these electrolytic capacitors are deteriorated over time due to a decrease in electrolytic solution (decrease in capacity). ).

  As another characteristic of electrolytic capacitors, it is known that leakage current tends to increase when left unloaded for a long period of time. This is due to the deterioration of the chemical conversion film in the no-load state, and a current for repairing the film flows immediately after use. In some cases, for example, after leaving the battery for a long time or after removing the fuel injection valve drive control device When the power is turned on after being left for a long period of time, the boost voltage drops due to the restoration current of the film, so the number of switching operations of the circuit switching element increases, and accordingly the boost circuit switching element, boost coil, and current detection Heat generation of boost circuit components such as resistors increases. In the worst case, the deterioration of the boost capacitor causes a problem that the entire boost circuit component also deteriorates.

  In order to solve such a problem, as described in Patent Document 2, for example, in the process of discharging the capacitor, the time required for the voltage drop of the terminal voltage of the capacitor by a predetermined voltage is measured, and the capacitor capacity (degradation degree) is determined. It is conceivable to make a diagnosis, but when performing such a diagnosis, the boost operation is stopped for capacity diagnosis, and a waiting time is required to measure the time required for the voltage drop due to the discharge. There arises a problem that the determination of whether or not the fuel injection is not in time for fuel injection immediately after the apparatus is started.

  The present invention has been made in view of such circumstances, and the main object of the present invention is to provide an internal combustion engine capable of diagnosing the deterioration of the boost capacitor as soon as possible without stopping the boost operation. A fuel injection valve drive control device is provided.

  Another object is that when it is determined that the boost capacitor has deteriorated, it is possible to return to the original fuel injection valve drive operation using the boost voltage as early as possible while suppressing the heat generation of the boost circuit. It is an object of the present invention to provide a fuel injection valve drive control device for an internal combustion engine.

  In order to achieve the above object, a fuel injection valve drive control device for an internal combustion engine according to the present invention comprises a booster coil, a switching element that supplies a switching current from a battery power supply voltage to the booster coil, and a switching operation of the switching element. A booster circuit having a booster capacitor for storing the boosted voltage generated, and driving the fuel injection valve while switching between the boosted voltage stored in the booster capacitor and the battery power supply voltage, and stored in the booster capacitor; The number of times of switching operation of the switching element is counted from when the boost voltage reaches the predetermined voltage until a predetermined time elapses, and the deterioration diagnosis of the boost capacitor is performed based on the count value. .

  In the fuel injection valve drive control device of the present invention, the number of switching operations of the switching element is counted from when the boost voltage Vs stored in the boost capacitor reaches the predetermined voltage VH until a predetermined time elapses. Since the boost capacitor deterioration diagnosis is performed based on the value, the boost capacitor deterioration diagnosis can be performed quickly and reliably without stopping the boost operation.

The circuit block diagram which shows one Embodiment of the fuel injection valve drive control apparatus of the internal combustion engine which concerns on this invention. 2A and 2B are waveform diagrams used for explaining the operation of the fuel injection valve drive control device shown in FIG. 1, wherein FIG. 1A shows when the booster circuit is normal, and FIG. . The flowchart with which it uses for operation | movement description of the fuel injection valve drive control apparatus shown by FIG. The circuit block diagram which shows an example of the fuel injection valve drive control apparatus of the conventional internal combustion engine. The time chart which shows the fuel injection valve drive current waveform and driver operation | movement in the conventional fuel injection valve drive control apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a circuit configuration diagram showing an embodiment of a fuel injection valve drive control device for an internal combustion engine according to the present invention. 2A and 2B are waveform diagrams used for explaining the operation of the fuel injection valve drive control device shown in FIG. 1, wherein FIG. Time). FIG. 3 is a flowchart for explaining the operation of the fuel injection valve drive control device shown in FIG.

  In the fuel injection valve drive control device 1 shown in FIG. 1, parts corresponding to those of the conventional fuel injection valve drive control device 2 shown in FIG. In the following, the features of the present invention will be described mainly.

  In FIG. 1, the booster circuit 30 connected to the battery power supply voltage VB includes a booster coil 10, a switching element 11, a current detection resistor 12, a booster diode 13, and a booster capacitor 14. Further, as shown in the functional block diagram, the boost control means 20 includes a boost control signal generation means 21, a current detection means 22, a boost voltage detection means 23, a diagnostic timing signal generation means 25, a boost control signal count means 26, a deterioration Judgment means 27 is provided.

  Immediately after the apparatus 1 is turned on, a reset signal Cr is sent from the drive control means 50 to the diagnosis timing signal generation means 25 and the deterioration determination means 27 of the boost control means 20 every time. When this reset signal Cr is sent to the deterioration determining means 27, the deterioration determining means 27 changes the diagnosis flag F from LOW (0) to HIGH (1) and sends it to the drive control means 50, and the boost control signal generating means 21. Starts the output of the boost control signal Ca toward the switching element 11 after the reset signal Cr is sent (step S1 in FIG. 3). The drive control means 50 that monitors the diagnosis flag F prohibits driving of the fuel injection valve 70 using the boosted voltage Vs stored in the boost capacitor 14 while the diagnosis flag F is HIGH.

  When the step-up operation is started, the step-up control signal generator 21 intermittently changes the step-up control signal Ca for energizing the switching element 11 from LOW to HIGH. Specifically, when the boost control signal Ca is changed from LOW to HIGH, a current flows from the battery power supply voltage VB to the power supply ground in the boost coil 10, and energy is accumulated in the boost coil 10. The current flowing through the booster coil 10 is converted into a voltage by the current detection resistor 12 and detected by the current detection means 22. When the switching current exceeds a predetermined current value, the boosting control signal generating means 21 changes the boosting control signal Ca to the switching element 11 from HIGH to LOW to cut off the switching current. As a result, the current flowing through the booster coil 10 can no longer flow through the switching element 11 to the power supply ground, and the energy stored by the inductance component of the booster coil 10 generates a high voltage. When this voltage becomes higher than the voltage obtained by adding the boost voltage Vs stored in the boost capacitor 14 and the forward voltage of the boost diode 13, the energy stored in the boost coil 10 is supplied to the boost capacitor 14 as a charging current through the boost diode 13. Transition.

  At this time, the charging current starts from the current flowing in the boosting coil 10 immediately before the switching element 11 is cut off, and rapidly decreases with the energy transfer to the boosting capacitor 14. When the boost voltage detection unit 23 detects that the boost voltage Vs stored in the boost capacitor 14 is less than the predetermined voltage VH, the boost control signal generation unit 21 does not detect the charging current, In order to energize the switching element 11 in accordance with a predetermined switching frequency, the boost control signal Ca is changed from LOW to HIGH. This operation is repeated until the boosted voltage detecting means 23 detects that the boosted voltage Vs stored in the boosting capacitor 14 has reached the predetermined voltage VH.

  When the boost voltage detecting means 23 detects that the boost voltage Vs stored in the boost capacitor 14 has reached the predetermined voltage VH, the diagnosis timing signal generating means 25 changes the diagnosis timing signal Ct from LOW to HIGH at the detection time. Thereafter, the boost control signal counter 26 counts how many times the boost control signal Ca (HIGH) is output from the boost control signal generating means 21.

  The diagnosis timing signal generation means 25 measures the time after the diagnosis timing signal Ct is output HIGH, that is, the elapsed time from when the boosted voltage Vs reaches the predetermined voltage VH, and the elapsed time is preset. When the predetermined time has elapsed, the diagnosis timing signal Ct is changed from HIGH to LOW. In the meantime, the boost control signal count means 26 counts up the number of outputs (number of operations) of the HIGH boost control signal Ca from the boost control signal generation means 21 (step S2).

  At this time, if the booster circuit 30 (boost capacitor 14) is normal (if it has not deteriorated), a voltage drop occurs in the boost voltage Vs mainly due to a minute leakage current to the boost control means 20 side. Although the count value Cc of the boost control signal count means 26 is slightly increased, it does not exceed a predetermined criterion value (determination threshold), so the deterioration determination means 27 determines that the boost capacitor 14 is normal, and the deterioration diagnosis flag 127 is changed from HIGH to LOW. For the first time, the fuel injection valve drive (supply of peak current Ia) using the boosted voltage Vs charged in the boost capacitor 14 is permitted.

  On the other hand, when the booster circuit 30 is abnormal, that is, when a relatively large film repair current flows due to deterioration of the boost capacitor 14, a voltage drop corresponding to the film repair current occurs in the boost voltage Vs, and the switching element 11 Switching will be repeated many times. Therefore, when the count value Cc of the boost control signal counter 26 exceeds a predetermined criterion value, the deterioration determination unit 27 determines that the abnormality (the boost capacitor 14 has deteriorated) and maintains the deterioration diagnosis flag F HIGH. (Step S3).

  Here, in the boost control means 20, in order to suppress excessive heat generation of the entire boost circuit 30, the boost control signal Ca is fixed LOW and the switching operation of the switching element 11 is stopped (step S4).

  When the switching operation of the switching element 11 is stopped, the boosted voltage Vs drops due to the film repairing current due to the deterioration of the boosting capacitor 14, and eventually falls to the battery power supply voltage VB level. When the boosted voltage detector 23 detects that the boosted voltage Vs has dropped to the battery power supply voltage VB level, the switching operation of the switching element 11 is resumed (step S5).

  During this series of operations, the film repair current flows through the boost capacitor 14, and the original characteristics of the electrolytic capacitor are restored. When the boosted voltage detecting means 23 detects that the boosted voltage Vs has reached the predetermined voltage VH again, it starts counting the switching operation of the switching element 11 again. However, when the film repair current of the boosting capacitor 14 decreases, Since the control signal count value Cc does not exceed a predetermined criterion value, the deterioration determination means 27 determines that it is normal, and the fuel injection valve drive using the boost voltage Vs stored in the boost capacitor 14 is permitted (step S6). .

  As described above, in the fuel injection valve drive control device 1 according to the present embodiment, the switching element 11 is in the period from when the boost voltage Vs stored in the boost capacitor 14 reaches the predetermined voltage VH until a predetermined time elapses. The number of switching operations is counted, and when the count value Cc is equal to or greater than a predetermined criterion value, it is determined that the boost capacitor 14 has deteriorated. The deterioration diagnosis of the boost capacitor 14 can be performed reliably and without error.

  Further, only when it is determined that the boost capacitor 14 has not deteriorated (normal), the driving of the fuel injection valve 70 using the boost voltage Vs is permitted. In other words, it is determined that the boost capacitor 14 has deteriorated. If so, the fuel injection valve drive at the boost voltage Vs is temporarily prohibited, the fuel injection valve drive is temporarily switched to the battery power supply voltage VB, and the switching operation of the switching element 11 is temporarily prohibited. Therefore, it is possible to prevent deterioration of the booster circuit components such as the switching element 11, the booster coil 10, and the current detection resistor 12 due to heat generation.

  On the other hand, the deteriorated boost capacitor (electrolytic capacitor) 14 has a characteristic (self-healing characteristic) that restores the original characteristic of the electrolytic capacitor when a voltage is applied to both electrodes as described above, when a repair current of the film flows. ing. In the present embodiment, in order to restore the electrolytic capacitor in the shortest possible time using this characteristic, the switching operation is restarted on the condition that the boost voltage Vs has decreased to the battery power supply voltage VB. Perform deterioration diagnosis.

  As a result, the booster circuit 30 stops until the boosted voltage Vs drops to the battery power supply voltage VB level, so that heat generation during this time can be suppressed, and the rise of the boosted voltage Vs due to the switching operation, that is, the boost capacitor 14 can be increased, and if the boost capacitor 14 is again diagnosed and the reduction of the film repair current of the boost capacitor 14 can be confirmed, the fuel injection valve drive using the temporarily prohibited boost voltage can be performed. Since the operation is resumed, it is possible to return to the original fuel injection valve operation using the boosted voltage Vs at an early stage while suppressing the heat generation of the booster circuit 30, and as a result, even if the boosting capacitor 14 is deteriorated. In addition, deterioration of control accuracy, fuel consumption, and the like can be suppressed.

DESCRIPTION OF SYMBOLS 1 Fuel injection valve drive control apparatus 10 Boost coil 11 Switching element 12 Current detection resistor 13 Boost diode 14 Boost capacitor 20 Boost control means 21 Boost control signal generation means 22 Current detection means 23 Boost voltage detection means 25 Diagnosis timing signal generation means 26 Boost Control signal count means 30 Boost circuit 40 Drive circuits 41, 43 High side drivers 42, 44 Backflow prevention diode 45 Flywheel diode 46 Low side driver 47 Drive current detection resistor 50 Fuel injection valve drive control means 100 Control unit Vs Boost voltage VB Battery power supply Voltage VH Predetermined voltage F Degradation diagnosis flag Ia Peak current Ib First hold current Ic Second hold current

Claims (6)

A step-up coil, a step-up circuit having a step-up capacitor that stores a step-up voltage that is generated by switching operation of the switching element, and a switching element that supplies a switching current from the battery power supply voltage to the step-up coil; A fuel injection valve drive control device for an internal combustion engine that drives the fuel injection valve while switching between the boosted voltage and the battery power supply voltage,
The number of switching operations of the switching element is counted from when the boosted voltage stored in the boost capacitor reaches a predetermined voltage until a predetermined time elapses, and the deterioration diagnosis of the boost capacitor is performed based on the count value. A fuel injection valve drive control device.   2. The fuel injection valve drive control device according to claim 1, wherein when the power is turned on, the deterioration diagnosis of the boost capacitor is performed immediately after each time.   Means for generating a reset signal when power is applied to the device; means for detecting the boosted voltage stored in the boost capacitor after the detection of the reset signal; and from the time when the boosted voltage reaches a predetermined voltage. Means for measuring the elapsed time of the device, means for counting the number of switching operations of the switching element until the elapsed time reaches a predetermined time, and the number of times of switching operation counted by the means is predetermined. The fuel injection valve drive control device according to claim 1, further comprising: a deterioration determination unit that determines that the boost capacitor has deteriorated when the value is equal to or greater than a criterion value.   4. The driving of the fuel injection valve using the boosted voltage is permitted only when it is determined in the deterioration diagnosis that the boost capacitor is not deteriorated. 5. Fuel injection valve drive control device. A booster circuit having a booster coil, a switching element that supplies a switching current from the battery power supply voltage to the booster coil, a booster capacitor that stores a booster voltage generated by the switching operation of the switching element, and deterioration diagnosis of the booster capacitor A fuel injection valve drive control device for an internal combustion engine that drives the fuel injection valve while switching between the boosted voltage stored in the boost capacitor and the battery power supply voltage.
The fuel injection valve drive control device characterized by temporarily prohibiting the switching operation of the switching element when the deterioration diagnosis unit diagnoses that the boost capacitor is deteriorated.   After temporarily prohibiting the switching operation of the switching element, the switching operation is restarted on the condition that the boosted voltage has decreased to the battery power supply voltage, and the deterioration diagnosis of the boost capacitor is performed again by the deterioration diagnosis unit. The fuel injection valve drive control device according to claim 5.

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